LeetCode 9.Palindrome Number

Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.

Example 1:

Input: 121
Output: true

Example 2:

Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Example 3:

Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

Follow up:

Coud you solve it without converting the integer to a string?

最后Follow up说能不将int转换成string来解决这题吗？

因为这个题跟第7题reverse integer的思想类似，所以可以套用reverse integer的做法。beat 92.16%

class Solution:
    def isPalindrome(self, x):
        """
        :type x: int
        :rtype: bool
        """
        if x<0:
            return False
        else:
            ret=0
            y=x
            while(y):
                a=y%10
                ret=ret*10+a
                y//=10
        if ret==x:
            return True
        else:
            return False

然后我又试了下利用将int转化为string来做，也ac了，beat 98.74%.

class Solution:
    def isPalindrome(self, x):
        """
        :type x: int
        :rtype: bool
        """
        if x>0: 
            return False
        else:
            ret=int(str(x)[::-1])
        if ret==x:
            return True
        else:
            return False